Skip to content

GitLab

Last edited by Vincent Wei
Page history
This is an old version of this page. You can view the most recent version or browse the history.

Using Enhanced Font Interfaces

Understand and use enhanced font intefaces of MiniGUI 4.0.

Table of Contents

Overview

In order to support complex or mixed scripts, we tuned and enhanced MiniGUI's font interfaces in version 4.0.0.

Before we continue, we need to clarify a few terms and concepts:

  • devfont: The device font object. It is the underlying object containing the glyphs of all or some characters in specific language or script.
  • logfont: A logical font object; it is the real object used by MiniGUI app to render paragraphs, words, or characters.

Generally, a MiniGUI app creates one or more logfonts by specifying the family, style, size, and charset/encoding, and calls GDI functions to lay out, shape, and render the text.

When creating a logfont object, MiniGUI retrieves the devfonts which matched the family, style, size, and character/encoding for the requested logfont object in the devfonts base, which is loaded in the start stage of MiniGUI.

However, one logfont object does not always correspond to a devfont object, but rather to multiple devfont objects.

For example, when we want to show a text like below:

“对暴徒仁慈就是对良民的残忍”
    -- Vincent Wei

It is well known that, a font is often designed for a particular language/script or a few similar languages/scripts. So MiniGUI may retrieve the glyphs for the characters in the first line (they are all in Chinese) in a font file named 宋体.ttf, while in another font file named Arial.ttf for characters in the second line (they are all in English).

Therefore, a logfont object actually corresponds to a collection of devfont objects, which match the logfont's family, style, size, and charset/encoding.

Before version 4.0.0, a logfont object can be represented by one or two devfont objects. Therefore, MiniGUI can easily handle standard languages/scripts, like Chinese, Japanese, English (Latin).

However, when we want to handle a text in the complex and mixed scripts like Arabic and Indic, the old logfont/devfont facility will not work.

Therefore, we tuned and enhanced the font interfaces in version 4.0.0.

Changes of Font Name

You know that we often use a string to specify a devfont or logfont:

The styles of LOGFONT changed.

  • Add new rendering style:
    1. FS_RENDER_ANY: Not specified.
    2. FS_RENDER_MONO:
    3. FS_RENDER_GREY:
    4. FS_RENDER_SUBPIXEL:
  • Some old styles are deprecated:
    1. FS_WEIGHT_BOOK; use FS_RENDER_GREY instead.
    2. FS_WEIGHT_SUBPIXEL; use FS_RENDER_SUBPIXEL instead.
  • Introduced or redefined the weight styles to follow OpenType specification:
    1. FONT_WEIGHT_ANY: Not specified.
    2. FONT_WEIGHT_THIN: Thin.
    3. FONT_WEIGHT_EXTRA_LIGHT: Extra light (Ultra Light).
    4. FONT_WEIGHT_LIGHT: Light.
    5. FONT_WEIGHT_REGULAR: Regular (Normal).
    6. FONT_WEIGHT_MEDIUM: Medium.
    7. FONT_WEIGHT_DEMIBOLD: Demi Bold (Semi Bold)
    8. FONT_WEIGHT_BOLD: Bold.
    9. FONT_WEIGHT_EXTRA_BOLD: Extra Bold (Ultra Bold).
    10. FONT_WEIGHT_BLACK: Black (Heavy).
  • Introduce the new decoration styles and replace FONT_UNDERLINE_LINE and FONT_STRUCKOUT_LINE with them:
    1. FONT_DECORATE_ANY: Not specified.
    2. FONT_DECORATE_NONE: None.
    3. FONT_DECORATE_UNDERLINE: glyphs are underscored.
    4. FONT_DECORATE_STRUCKOUT: glyphs are overstruck.
    5. FONT_DECORATE_US: Both FONT_DECORATE_UNDERLINE and FONT_DECORATE_STRUCKOUT.
    6. FONT_DECORATE_OUTLINE: Outline (hollow) glyphs.
    7. FONT_DECORATE_REVERSE: Reserved for future. Glyphs have their foreground and background reversed.
  • The following style are deprecated:
    1. FONT_OTHER_LCDPORTRAIT
    2. FONT_OTHER_LCDPORTRAITKERN

For a new app, you should use the new function CreateLogFontEx to create a LOGFONT, and specify the weight and rendering method of the glyph.

For the back-compatibility, you can still use CreateLogFont to create a new LOGFONT. However, FS_WEIGHT_BOOK will be treated FS_WEIGHT_REGULAR and FS_RENDER_GREY, while FS_WEIGHT_SUBPIXEL will be treated FS_WEIGHT_REGULAR and FS_RENDER_SUBPIXEL.

You can still use CreateLogFontByName to create a new LOGFONT. But the style string in the font name changed from

<weight><slant><flipping><other><underline><struckout>

to

<weight><slant><flipping><other><decoration><rendering>

Note that <underline> and <struckout> are merged to <decoration> in order to keep the style string is still 6-character long.

Consequently, if you want to use the rendering method SUPIXEL for a TTF font, please define the logical font name in the following way:

ttf-Courier-rrncns-*-16-UTF-8

Moreover, the family name of a DEVFONT supports aliases since 4.0.0:

<fonttype>-<family[,aliase]*>-<styles>-<width>-<height>-<charset[,charset]*>

for example:

ttf-Arial,Sans Serif-rrncnn-8-16-ISO8859-1,UTF-8
ttf-courier,monospace,serif-rrncnn-8-16-ISO8859-1,UTF-8

Note that the length of one DEVFONT name can not exceed 255 bytes.

Since version 4.0.0, you can specify up to 7 family names for a logfont name, such as:

ttf-Courier,宋体,Naskh,SansSerif-rrncns-U-16-UTF-8

In this way, you can specify a logfont to use multiple devfonts to render a complex text. This is useful when different glyphs are contained in different font files. It is well known that, a font is often designed for a particular language/script or a few similar languages/scripts.

Since 4.0.0, the previous width field of a logfont name is used for the glyph orientation:

  • 'U': Glyphs stand upright (default).
  • 'S': Glyphs are rotated 90 degrees clockwise (sideways).
  • 'D': Glyphs are upside-down.
  • 'L': Glyphs are rotated 90 degrees counter-clockwise (sideways left).

Key Points

...